All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu 'alyhi wa sallam, is His slave and Messenger.
The Sharee‘ah does not approve of evildoing and thus it must be changed. In fact, there are many degrees of changing evil in the same way that people may have different abilities; however no one is excused for not forbidding evil. This is because the person should change evil with his hand. If he cannot, he should change it with his tongue. If he cannot, he should change it with his heart. This last act can be done by all people except those whose hearts are diseased and corrupted.
It was narrated that the Prophet, sallallaahu ‘alayhi wa sallam, ordered anyone who sees an evil thing to change it with his hand. If he cannot, he should change it with his tongue. If he cannot, he should change it with his heart, and this is the weakest degree of faith. [Muslim]
The meaning of “the weakest degree of faith” is that it is the least fruitful, as what was mentioned by An-Nawawi and Al-Mubaarkafoori . As-Sindi said that it means that denouncing evil with the heart is the weakest thing that can be done; it does not mean that the person’s faith is weak because this imight be the only thing he can do. Al-‘Izz ibn ‘Abdus-Salaam said that this Hadeeth urges believers to achieve a higher degree than denouncing evil with one’s heart. Ibn Hazm said that it means that there is no faith beyond that.
In conclusion, this Hadeeth essentially addresses the changing of evil, so a person should change evil by any means possible, whether by words or actions, otherwise the person should at least denounce it in his heart.
Allaah Knows best.